Outdoor furniture and fixtures exposed to public use and vandalism generally require an extremely durable structure. Such outdoor furniture and fixtures are often constructed of steel so as to provide the necessary structural strength and durability. Steel furniture and fixtures are prone to rust if not adequately protected against rusting. It is conventional to paint outdoor metallic fixtures with protective coatings so as to enhance the aesthetic features and protect the metallic furniture and fixtures against rusting. It is also conventional to paint such furniture and fixtures with paints formulated with thermoplastic film-forming substances. Unfortunately, the painted coatings are thin and prone to scratching or paint removal which mars the appearance and exposes the underlying metal to rusting.
Recreational picnic benches and tables, outdoor playground equipment, outdoor furniture, and other similar outdoor fixtures (generally referred to as fixtures herein) are exposed to extensive wear and tear and, therefore, by necessity require a very durable protective coating. Accordingly, more durable protective coatings than the conventional thermoplastic painted coatings is needed. It has, heretofore, been conventional to coat such outdoor furniture, and fixtures with a relatively heavy coating or overcoating of plasticized polyvinyl chloride generally known as plastisols, so as to provide more durable protection against physical wear. Unfortunately, polyvinyl chloride (PVC) coated fixtures, when exposed to sunlight and outdoor weathering conditions will inherently undergo chemical, physical and microbiological decomposition. Although pieces freshly coated a polyvinyl chloride coating typically exhibit a superior external appearance, exposure to hot and humid conditions (especially when disposed at a horizontal positioning) may result in rapid deterioration of the protective coating. This surface deterioration first appears as small black spots that slowly spreads over time. Subsequently, the PVC surface deterioration progresses to an "alligator hide" appearance. Such surface deterioration is often due to either fungal attack or ultraviolet (UV) degradation. Certain atmospheric borne corrosive chemicals, such as those commonly associated with acid rains, will also cause deterioration of the PVC coating.
Fungal attack is most prominent in hot and humid condition, such as commonly prevelant in southeastern section of the United States. Evidence of this phenomena is a "blackening" of vertical and horizontal positioned surfaces. Various types of microorganisms (particularly fungus), usually from the soil cling to the PVC surface, consume the plasticizer, culture and spread. Within months this can appear as an ever enlarging black area. A fungal retardant formulated in the polyvinyl chloride composition will inhibit or arrest fungal growth; however, it is expensive and usually entails a toxic fungicide such as arsenic.
Ultraviolet (UV) degradation prominently occurs in hot and arid conditions such as commonly prevalent in the southwestern section of the United States. A special type of ultraviolet degradation usually occurs only on horizontal surfaces and involves a slower degradative process than fungal deterioration. According to certain researchers, UV degradation may be attributed to the following factors:
A. Dirt accumulates and remains on horizontal PVC coated surfaces; PA1 B. Dirt extracts (absorbs) plasticizer which accumulates on the surface; PA1 C. Plasticizer is then degraded and photosynthesized by the sunlight; and PA1 D. The degraded plasticizer catalytically degrades the fused PVC coating. PA1 a) priming the metal base of the fixture so as to provide a primed metal base with a primed surface adapted for applying the polymeric coating; PA1 b) coating the primed surface with a plasticized polyvinyl chloride coating composition to provide a metal base product coated with the plasticized polyvinyl chloride coating; and PA1 c) applying an overcoating barrier to the product so as to protectively shield the polymeric coating from atmospheric exposure.
Formulating the PVC coatings with UV screeners will retard the UV degradation but will not effectively overcome the UV degradation problem.
Consequently, plasticized polyvinyl chloride coatings will typically undergo extensive discoloration and exhibit a dramatic change in external appearance upon exposure to these adverse weathering conditions. As indicated, these deterioration problems are accelerated by humid and warm climatic conditions, such as commonly prevalent in the southeastern regions of the United States of America. Metal furniture and fixtures coated with a protective polyvinyl chloride coating in such regions often become marred in appearance with pronounced blackened spots, which upon further weathering and aging, will become grotesquely discolored and unsightly in appearance. Attempts to formulate the coatings with fungicides and other microbiological preservatives have been ineffective. There exists a need to effectively protect plasticized polyvinyl chloride coatings formulated with conventional plasticizing reagents from chemical, fungal and UV degradation.
These degradative problems are compounded in outdoor playground equipment such as elevated decks, bridges, and ladders coated with the PVC. Treading upon the surface by children at play contributes to dirt accumulation and often wetness which conditions are particularly conducive to PVC degradation. Moreover, the surfaces may become slippery and unsafe especially when wet. Such slippery surfaces are accident prone and can be dangerous to young children. In PVC coated playground equipment there not only exists a need to protect PVC surfaces from degradation but a need to improve upon surface traction, thus improving safety by reducing potential accidents caused by slipping.